Silanetriols as powerful starting materials for selective condensation to bulky POSS cages

Abstract

Controlled condensation reactions of tertiary silanetriols CH 3 (CH 2) n (CH 3) 2 CSi(OH) 3 (1b-f; n = 1-5) in the presence of trifluoroacetic acid and the hydrolysis of CH 3 (CH 2) 6 (CH 3) 2 CSiCl 3 (3) lead to the selective formation of the corresponding disiloxane tetrols [CH 3 (CH 2) n (CH 3) 2 CSi(OH) 2 ] 2 O (2b-g; n = 1-6) in good yields. The TBAF-driven condensation reactions of the silanetriols CH 3 (CH 2) n (CH 3) 2 CSi(OH) 3 (1a-c; n = 0-2) as well as of the disiloxane-1,1,3,3-tetrol 2d (n = 3) yield in the selective formation of the first T 8 cages bearing tertiary carbon substituents, CH 3 (CH 2) n (CH 3) 2 C (4a-d; n = 0-3), which was not possible via the condensation of their alkoxysilane counterparts so far. The resulting compounds 2b-g and 4a-d have been characterized by multinuclear NMR, MS, and single-crystal X-ray diffraction.